Automatic drip brewing devices prepare coffee or tea by controlled delivery of heated water from a water reservoir through a porous filter holding coffee or tea in a filter basket which drains into a separate receptacle such as a carafe or pitcher which is not connected to the device. The brewed beverage is then poured from the pitcher. A warming element in a base on which the pitcher rests transfers some heat to the brewed beverage. However, pitchers constructed of glass or metal are not well insulated and therefore the warming element is not sufficient to keep the brewed beverage hot.
Automatic drip brewing devices intended primarily for home use are dimensioned to produce and hold relatively small quantities of brewed beverage in a pitcher or carafe, such as a total of eight to ten cups produced in a single brewing cycle. The relatively small size of the pitchers of such devices allows for lifting and pouring. This arrangement is therefore not suitable for preparing larger quantities, such as more than ten cups, of brewed beverage in a single brewing cycle for the reasons that a pitcher receptacle of sufficient volume becomes difficult to handle and adequately insulate.
Commercial automatic drip brewing devices, such as for example the Bunn Model No. CWTF-20, use a relatively large capacity (e.g., 20 cups) free-standing metal brewed beverage receptacle fitted with a spigot for dispensing the beverage from the receptacle. The metal receptacle, however, is generally not well insulated nor partially surrounded by a water reservoir. Also, the metal receptacle must have an opening in the top through which the brewed beverage enters by dripping. Heat is lost through this opening.